”turn over a new leaf”
to begin again, fresh; to reform and begin again; to start behaving in a better way
از نو شروع کردن، از سر گرفتن، شروعی دوباره داشتن
Example 1: I have made a mess of my life. I’ll turn over a new leaf and hope to do better.
Example 2: Apparently he’s turned over a new leaf and he’s not smoking any more.